This invention relates to mirrors and to a process of manufacturing mirrors.
The mirrors of this invention may have various applications, for example: domestic mirrors used for example in furniture, wardrobes or bathrooms; mirrors in make-up boxes or kits; mirrors used in the automotive industry, as rear-view mirrors for cars, for example. Such mirrors may be produced by applying a silver coating on glass sheets, particularly on soda lime glass, flat glass or float glass.
Conventionally, silver mirrors have been produced as follows: the glass was first of all polished and then sensitised, typically using an aqueous solution of SnCl2; after rinsing, the surface of the glass was usually activated by means of an ammoniacal silver nitrate treatment, and a silvering solution was then applied in order to form an opaque coating of silver; this silver coating was then covered with a protective layer of copper and then with one or more coats of leaded paint in order to produce the finished mirror. The combination of the protective copper layer and the leaded paint was deemed necessary to provide acceptable aging characteristics and sufficient corrosion resistance.
More recently, Glaverbel developed mirrors which dispensed with the need for the conventional copper layer, which could use substantially lead-free paints and yet which still had acceptable or even improved aging characteristics and corrosion resistance. For example, U.S. Pat. No. 6,565,217 describes embodiments of a mirror with no copper layer which comprises in the order recited: a vitreous substrate; both tin and at least one material selected from the group consisting of palladium, bismuth, chromium, gold, indium, nickel, platinum, rhodium, ruthenium, titanium, vanadium and zinc provided at a surface of the vitreous substrate; a silver coating layer on said surface of the substrate; at least one material selected from the group consisting of tin, chromium, titanium, ion, indium, copper and aluminium present at the surface of the silver coating layer which is adjacent to an at least one paint layer; and at least one paint layer covering the silver coating layer. Such mirrors provided a significant advance with respect to conventional coppered mirrors. Nevertheless, during transportation, handling and on cutting tables, care has to be taken with respect to such mirrors to avoid scratches in the paint layer and/or in the silver layer. Furthermore, such mirrors are compatible with and chemically resistant to only some types of adhesive available on the market.